Compact housing for rotary compressor system

ABSTRACT

A rotary compressor assembly constructed to prevent leakage from the compressor housing to atmosphere through the interface between the cylindrical section and the covers of the housing. 
     The compressor is disposed substantially within the tank which receives the compressor discharge and is connected to the wall of the tank. A seal between the compressor and the tank wall seals the tank and thereby prevents leakage from the compressor to atmosphere.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to compressors and particularly to devicesadapted to prevent leakage of the air or gas being compressed bysubmerging or surrounding the compressor mechanism or some portionthereof in a fluid.

2. Description of the Prior Art

In the construction of sliding vane rotary type compressors, theclearance between the end of the rotor and the end covers of thecompressor housing is critical to the functioning of the device. If thisclearance is too large, gas compressed in the pocket formed by cylinderwall of the compressor housing, the rotor, adjacent sliding vanes andthe end covers of the compressor housing will leak from one pocket tothe adjacent pocket of lower pressure, substantially reducing theefficiency and output of the compressor. If the tolerance between theend of the rotor and the end covers of the housing is too small, therewill be an interference of the parts which can result in damage to themachinery as well as reduced performance. In view of these facts, it isnot unusual to find that maching tolerances measured in the tenthousandths of an inch (0.0001) are required in order to properlyposition the end covers to the cylindrical section of the compressorhousing.

Because the tolerances are so important, it is not possible to use anygasket type sealing means between the end covers of the compressorhousing and the cylindrical section of the housing to prevent leakagefrom the compressor to the atmosphere. The interposing of any.Iadd.gasket .Iaddend.between the end covers and the cylindrical sectionwould place a component of variable dimension in the chain of elementswhose overall dimension must be held to within the above mentioned tenthousandths of an inch.

Therefore, to provide sealing between the front cover of the compressorand the compressor housing, the prior art had to use an O-ring type sealdisposed between the circumferential surface of the front cover and theinner wall of the cylindrical section of the compressor housing. Thistype of construction is shown in FIG. 2 of U.S. Pat. No. 3,385,513issued May 28, 1968 to C. R. Kilgore where an O-ring 20 is disposedbetween the outer wall 11 of the housing and the front cover 13a.

The problems with this type of sealing arrangement are the relativeinefficient seal provided by an O-ring seal assembly as compared to agasket sealing assembly, and the rapid deterioration of the O-ringsealing member as compared to a gasket sealing member for this type ofapplication. The latter factor results from hardening, cracking andpermanent deformation of the O-ring due to the heat, air and oil towhich the O-ring is exposed in a typical compressor application.Additionally, it is often necessary to remove the covers of thecompressor for periodic servicing of the vanes and bearings within thecompressor, and therefore the covers must be slid out of engagement fromthe cylindrical section of the housing thereby rubbing and scuffing theO-ring seal along the inner wall of the housing.

To overcome the problems of the prior art the applicant has provided anew, improved construction for a rotary compressor in which leakage fromthe compressor to atmosphere through the interface between thecylindrical section of the compressor housing and the covers of thecompressor housing is prevented by a gasket type sealing means withoutin any way effecting the relative position of the front cover to thecompressor rotor.

A new construction accomplishes this end by placing the compressorhousing substantially in the tank which receives the compressordischarge and seals the front cover of the compressor with a gasket-typeseal to the wall of the receiver tank. By this construction, theinterfaces between the cylindrical section of the compressor housing andthe covers of the housing are located in an enclosed area sealed fromthe atmosphere. A gasket-type seal can be used to seal the front coverof the compressor to the tank, without effecting the performance of thecompressor in any way, to prevent leakage from the tank to atmosphere.If any leakage does occur it would be "inward" leakage from thedischarge tank back into the compressor housing. This inward leakage ismuch less serious then a comparable conventional leakage from thecompressor housing to atmosphere since the inward leakage does not haveas great an effect as conventional leakage on compressor efficiency andoutput.

Accordingly, it is an object of the present invention to provide acompressor assembly in which no special intervening sealing medium isrequired between the covers of the compressor housing and thecylindrical section of the compressor housing to effectively seal theinterfaces between these elements from the atmosphere.

Another object of the present invention is to provide a compressorassembly in which the compressor is substantially located within thetank which receives the compressor discharge.

Yet, another object of the present invention is to provide a compressorassembly in which the sealing means to prevent leakage from thecompressor housing to the atmosphere can be effected by gasket typesealing means without adversely effecting performance or efficiency ofthe compressor.

Still another object of the present invention is to provide a compressorsystem in which the clearance between the compressor rotor and the frontcover of the compressor is not affected by the means used to sealleakage from the compressor to the atmosphere through the interfacebetween the covers and the cylindrical section of the compressorhousing.

A further object of the present invention is to provide a compressorassembly which does not require a separate line from the outlet of thecompressor to the tank which receives the compressor discharge.

Yet, a further object of the present invention is to provide acompressor assembly having a compact envelope in which the tank whichreceives the discharge of the compressor also acts as an oil sump forthe lubrication system of the compressor.

Still a further object of the present invention is to provide acompressor assembly in which the tank which receives the discharge ofthe compressor contains means to separate oil from the discharge of thecompressor and acts as a sump for the lubrication system of thecompressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a compressor assembly built in accordance withthe teachings of this invention.

FIG. 2 is an enlarged view of FIG. 1 partially in section.

FIG. 3 is a view taken along lines 3--3 of FIG. 2.

FIG. 4 is an enlarged fragmentary view of a portion of FIG. 2.

FIG. 5 is a view taken along lines 5--5 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIGS. 1 through 5, a compressor generally indicated at 10 ismounted in a tank generally indicated at 12 which receives the dischargefrom the compressor and is driven by an electric motor 14 through ashaft assembly 16, all of which are mounted on top of a compressed gasstorage tank 18 and are controlled from control panel 20. Thecompressor-tank combination is positioned with relation to electricmotor 14 by fastening all of the units to a mounting frame 22 which inturn is fixed to tank 18 by means of legs 24 on the mounting frame whichare welded or connected by any other convenient method to arms 26protruding from the compressed air storage tank. Control panel 20 isconnected to mounting frame 22 by bracket 28, while tank 12 by means oflegs 30 is connected to mounting frame 22 by welding or any other meansof attachment such as bolting or vibration mounts, etc. Motor 14 isfastened to pedestal 32 by means of bolts 34 to coaxially position themotor 14 and the compressor 10. A flexible coupling 35 in shaft assembly16 compensates for any slight misalignment between the compressor andmotor. A radiator 36 whose function will be explained later is connectedto mounting frame 22 by means of brackets 38 which are bolted to thebase of the radiator by bolts 40 and are connected to the mounting frameby welding or any other convenient methods of attachment.

Mounted substantially within compressor discharge tank 12 are thecompressor 10 and air oil separator 42 which separates out the oil mixedin the discharge of the compressor from the compressed gas before thecompressed gas passes from the receiving tank 12 through line 44 to thecompressed gas storage tank 18. The oil separated by the air oilseparator 42 drops to the sump portion at the bottom of tank 12. Tank 12consists of three sections, a cylindrical portion 46, an end plate 48 inwhich demister 42 is mounted, and a front wall 50 in which thecompressor 10 is mounted as will be further explained below.

As seen from FIGS. 2 through 5 the compressor 10 has a cylindricalsection of the compressor housing generally indicated at 52, a rearcover 53 including an end plate 55, and an inlet housing 54 on the frontcover 56 of the compressor. The compressor is of the rotary vane typehaving a compressor rotor 58 with sliding vanes 60 mounted therein andit is driven by the end 62 of shaft assembly 16 which delivers powerfrom motor 14. Air to be compressed enters the inlet assembly throughair cleaner 64 which is connected by fitting 66 to the suction controlassembly 68 which throttles the inlet gas flow to the compressor inresponse to the pressure in storage tank 18 to unload compressor 10during periods of nonoperation. The suction control assembly 68 isconnected to inlet housing 54 by inlet pipe 70. The fluid to becompressed after reaching the inlet housing 54 passes through thesuction inlet opening 72 in front cover 56 to enter the cylinder of thecompressor. Compression occurs in the cylinder in the normal mannerfound in a rotary compressor, namely by varying the volume of the pocketformed between the adjacent vanes extending from the compressor rotorand the inner wall of the cylindrical section of the housing of thecompressor. The pocket varies in size during the rotary cycle of therotor, diminishing as compression occurs until the compressed air isexhausted from the compressor housing at a point not shown in thedrawings.

Oil which has been separated from the compressor discharge by bafflemeans in the tank (not shown) and air oil separator 42 falls to the sumpportion of tank 12 and because of the high pressure in the tank isforced through conduit 74 to radiator 36 where the oil is cooled andthen returns to the inlet of the compressor. Fan 76 driven by shaftassembly 16 pushes air through radiator 36 to produce the necessarycooling. A shroud 78 on the radiator increases the efficiency of thefan, and a shield 80 is mounted around the fan for purposes of safety.

Sealing of Interface Between Compressor Housing and Atmosphere

As shown from FIGS. 2, 3 and 4, the front cover 56 of compressor 10consists of a sealing flange 82, a shaft seal housing 84 and a shaftseal housing cover 86 connected to shaft seal housing 84 by bolts 88 orany other convenient fastening means. A gasket 90 maintains an air tightseal between the shaft seal housing and the shaft seal housing cover.The shaft 62 passes through the shaft seal housing cover and rear wall92 of the shaft sealing housing to drive the compressor rotor 58. Amechanical seal 94 attached to shaft 62 coacts with collar 96 on theshaft seal housing cover to maintain an airtight seal between theinterior of the shaft seal housing and the atmosphere. As seen in FIG.2, front cover 56 of compressor 10 is connected by through bolts 98 tothe flange 100 protruding from the rear cover 53 of the compressorhousing thereby holding cylindrical section 52 of the compressor housingin operative position between the ends of the compressor.

The front cover 56 of the compressor housing is aligned in thecylindrical section 52 of the compressor housing by means of a step 104on the front cover of the compressor which is concentrically fittedwithout lip 102 on the end surface of the compressor housing 52.

The abutting surfaces on lip 102 of compressor housing 52 and on step104 of front cover 56 are carefully machined to provide a seal betweenthe housing and the cover. A similar arrangement not shown in thedrawings is used to align and seal the rear cover 53 to the cylindricalportion of the housing.

The compressor 10 is mounted to the tank by means of sealing flange 82of front cover 56 which is connected to front wall 50 of tank 12 bymeans of bolts 106. A seal is effected between the inner space of tank12, which receives the compressor discharge and the ambient atmosphereby a gasket seal 108 which is disposed above the opening in wall 50 ofthe tank.

Since no sealing medium need be interposed between either end 53 or 56and the cylindrical section 52 of the compressor housing, the distancebetween the inner wall 110 of front cover 56 and the inner wall of rearcover 53 (not shown in the drawings) can be accurately set andmaintained for the life of the compressor. Therefore, the position ofthe compressor rotor 58 relative to the inner surface 110 of the frontcover 56 and the corresponding surface of the rear cover 53 is alsouneffected. This is a significant advantage because the clearancebetween the ends of the compressor rotor and the vanes therein and theinner surfaces of the front and the rear covers is of prime importancefor effective operation of a compressor, as previously explained.

It should be noted that sealing the front cover of the compressor to thefront wall of the tank prevents any leakage from the interfaces of thecompressor housing to the ambient atmosphere but instead exposes thecompressor housing interfaces to the pressure within the tank. Any"inward" leakage which does occur from the tank into the compressorhousing will be much less serious for the effective performance of thecompressor than would a comparable amount of leakage from the compressorhousing to the atmosphere.

It should also be noted that placing the compressor substantially withinthe tank which receives the compressor discharge has other advantages asfor example, drastically reducing the overall size of the compressorassembly package. Additionally, by locating the compressor within thedischarge package it is significantly easier to soundproof or suppressthe noise produced by the rotary compressor.

It should be further noted that the invention set forth above is notlimited to sliding vane type rotary compressors. The invention isequally applicable to rotary screw type compressors.

It will be understood that various changes in the details, materials,and arrangements or parts which have been herein described andillustrated in order to explain the nature of the invention may be madeby those skilled in the art without the principle and scope of theinvention, as expressed in the appended claims.

I claim:
 1. A rotary compressor assembly comprising:tank means forreceiving compressed fluid, said tank means having one wall defining anopening and inner and outer wall surfaces, said tank means also having adischarge outlet for compressed fluid; fluid compressing means includinga housing disposed to extend into said opening in said tank means and arotor mounted within said housing; a drive means for said compressingmeans, said drive means including a drive shaft connected to said rotor;said compressing means having an inlet disposed at a point external tosaid tank means and an outlet within said tank means to permitcompressed fluid to be discharged therein; .Iadd.demister means mountedin said tank means for separating out oil mixed in the discharge fromsaid fluid compressing means; .Iaddend. said compressing means housinghaving cover means at the opposite ends thereof, one cover means beingconnected to the inwardly disposed end of the housing and the othercover means being connected to the opposite end of the housing and theone wall of the tank at the periphery of the opening, said other covermeans coacting with said housing and said rotor to provide an operativeseal between the outward end of said rotor and said other cover means;sealing means located between one of said wall surfaces and theconfronting surfaces of said other cover means adjacent the opening inthe one wall of said tank means; means providing a mechanical seal forsaid drive shaft at a point outboard of said other cover means; andmeans to connect said other cover means at one end of said housing tosaid tank means about said opening for mounting said compressing meansin operative relation to said tank and to permit said cover means andsaid sealing means to form a fluid tight cover for said opening in saidtank means, and thereby prevent leakage from said compressing meanshousing to atmosphere.
 2. The combination claimed in claim 1 whereinsaid sealing means is connected to the outer wall surface of the onewall on said tank means.
 3. The combination claimed in claim 1wherein:said other cover means includes a sealing flange; and saidsealing means comprises gasket means disposed between said sealingflange of said other cover means and the one wall of said tank.
 4. Thecombination claimed in claim 3 wherein said sealing flange of said othercover means is disposed outside the one wall of said tank means.
 5. Thecombination claimed in claim 4 wherein the inlet of said compressorhousing is disposed in said other cover means connected to said tankmeans about said opening.